Chiller PLC Refurbishment
Chiller refurbishment of blown PLCs can easily be carried out by Maximus Chillers. At Head Office, we have an electronics laboratory where our dedicated controls engineer strips down and inspects your PLC. A programmable logic controller will often fail for basic reasons, such as, a component going to earth. Usually this occurs outside the controller or relay board. The volt leakage draws down the 5 vdc to earth, causing over heating then overload of PCB components. Higher voltage earth drawdown such as 24v, 110v and 240v also occurs because the PLC is used to switch various relays and contactors around the chiller.
Don't Blow the PLC!
Before we fit the refurbished PLC, let's have a look at why it failed in the first place. Most commonly rain water has got into a component such as the plug that screws onto a solenoid. The fault can be traced by assessing how the PLC or relay board failed, then fault finding the chiller using a multimeter. It would be rather embarrassing to fit a refurbished controller and then blow it again after switching the machine on!
A larger machine will have a refurbished controller that cannot fail due to problems around the chiller. This is because it is separated by relays and contactors. Should anything go to earth, the PLC is protected by this step in between. The components that do go directly into the controller: the slide valve sensor for example, have a milliamp fuse for protection.
Failures From Within the Controller
Although the most common reason to refurbish a controller is earth leakage, the electronics can slowdown or fail completely from within the controller. Dust can cause 'tracking' across a printed circuit board, causing internal failure of components. Also, issues to the line voltage can cause the wrong volts to come out of the other side of a transformer. This can corrupt the program, causing 'ghost lights' and malfunctions. All of this is checked prior to the controller refurbishment, to ensure the job goes as it should. 12 month guarantee on all of our refurbished controllers.
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Case Study of Chiller Refurbishment
We recently carried out refurbishment to a controller for a large chiller. The controller was slow and did not receive inputs from the user all the time. It also regularly showed ‘ghost faults' that were not present.
Remove and Ship
The controller was disconnected from the machine and the hole in the panel weather proofed with sticky back plastic. It was then bubble wrapped and took back to our electronics laboratory.
Diagnose and Rectify the Circuit Board
When the controller was plugged in to our test equipment, the circuit board was fault found to identify the failed components. Various components had been overheated and burned out. These components were replaced with our off the shelf stock. The reasons for the burnouts were identified and rectified. The internal frame and caddy were fitted and the controller was put back together.
We then set up a test rig and tested the controller. Volts in of 24 vac was noted on our form. Then, 5vdc out of the onboard transformer and inverter was also recorded. There was minimal heat gain to the heat sink, so we determined that the controller was functioning efficiently. The CAT 5 plug connection which connects to the relay module was tested to ensure that the controller will function correctly in the field.
One of our carriers specialises in the shipping of electrical equipment. We knew we could trust in them that the controller would be carried gently during transit. Before collection, the controller was again bubble wrapped and boxed.
Refitting the Controller
On arrival, the controller was removed from its packaging. The weatherproofing was removed from the chiller and the controller was refitted into the panel. The controller is only splash resistant not rain proof, so a cover is available to screw over the top. The line voltage was plugged back in and the correct run signal and data signal was checked to the relay module. The relays were individually fired from the controller and all were functioning as they should.
There are password protected menu levels available for the controller and a master password level. The parameters for each menu were assessed and saved. During the running of the machine, they were adjusted to ensure the reliable running of the plant. After several hours of monitoring the controller worked perfectly and the machine went back into seamless operation.
Why Choose Us for Chiller Refurbishment?
With an excellent pool of knowledge and the latest quality equipment- Maximus Chillers can help.
Any Chiller- Any Problem- Any Part- Any Refrigerant- Anywhere- The MAXIMUS ADVANTAGE™
What We Offer for Chiller Refurbishment
A service that will keep your plant running beyond any obstacle, at a fraction of the cost of new plant.
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